ES3010537T3 - Container handling vehicle comprising a container carrying position, associated system and methods - Google Patents

Abstract

A container handling vehicle (401) is described for operation on a two-dimensional rail system (108) comprising a first set of parallel rails (110) arranged to guide the movement of the container handling vehicle (401) in a first direction (X) through the top of the frame structure (100), and a second set of parallel rails (111) arranged perpendicular to the first set of rails (110) to guide the movement of the container handling vehicle (401) in a second direction (Y) that is perpendicular to the first direction, dividing the rail system (108) into a plurality of grid cells (122) by the first and second sets of parallel rails (110, 111), wherein the container handling vehicle (401) comprises: - a wheelbase unit (2) comprising a first and second set of wheels (32a, 32b) for guiding the container handling vehicle (401) to along the railway system (108) in the first and second directions (X, Y) respectively, wherein the first and second wheel assembly (32a, 32b) forms the outer periphery of the base unit (2); a body unit (410) comprising: a lower section (411) disposed in the base unit (2), having a horizontal surface equal to or less than that of the base unit (2), and an upper surface (425) providing a first container loading position (425) for transporting a storage container (106); a support section (412) extending vertically from the lower section (411), having a horizontal surface less than that of the lower section (411); and a cantilever section (413) extending horizontally from the support section (412) beyond the surface of the lower section (411). and a lifting device (414) comprising a lifting frame (415) suspended from the cantilever section (413). An associated automated storage and retrieval system is further described, as well as methods for transferring a storage container (106) between a first and a second container handling vehicle (401), and between said vehicle (401) and an external conveyor belt.

Description

DESCRIPTION

Container handling vehicle comprising a container transport position, system and associated methods

Field of the invention

The invention relates to the field of automated storage and retrieval systems. In particular, the invention relates to a container handling vehicle with a cantilever section and to an automated storage and retrieval system comprising a plurality of container handling vehicles, wherein the container handling vehicles have at least one additional storage position compared to prior-art container handling vehicles of the cantilever type. Furthermore, transfer of a storage container between a first and second container handling vehicle, as well as transfer of a storage container between a container handling vehicle and an external container transport position, are described.

Background and state of the art

Patent document WO2019/137870 describes, according to its abstract, an automated storage and retrieval system comprising a container handling vehicle comprising a transport mechanism for transporting the vehicle on the rail system. The container handling vehicle further comprises a lifting assembly for picking up storage containers from storage columns to a position above the lowest level of the transport mechanism, wherein the lifting assembly comprises a lifting frame connectable to a storage container, a first lifting shaft and a second lifting shaft of equal or nearly equal diameter. The first and second lifting axes are substantially parallel, and each of the first and second lifting axes is supported on an upper portion of the vehicle. Two lifting elements extend from each of the first and second lifting axes to the lifting frame, a motor drive assembly comprising at least one first motor, wherein the at least one first motor surrounds one of the lifting axes. A force transfer assembly rotatably connects the first and second lifting shafts via a force transfer element. It further describes a container handling vehicle, as well as a method for operating the automated storage and retrieval system.

Patent document WO2019/238703 describes, according to its abstract, a storage system comprising a storage grid comprising vertical column profiles defining a plurality of grid columns, the grid columns comprising storage columns, in which storage containers can be stored one on top of the other in vertical stacks. The storage grid comprises at least one grid of rails at the upper ends of the column profiles, a first container handling vehicle and a second container handling vehicle, the first and second container handling vehicles comprising at least one wheel base unit and a first container handling module or a second container handling module, respectively, connected to the wheel base unit. Each wheel base unit has a wheel arrangement for movement of the wheel base unit in two perpendicular directions on a rail grid of the storage system, and a horizontal periphery that fits within the horizontal area defined by a grid cell of the rail grid such that the wheel base units can pass each other in any adjacent grid cell of the rail grid, each of the wheel base units comprising an upper surface configured as a connection interface for connection to any one of first and second container handling modules, and the first container handling module is a different type of container handling module than the second container handling module.

Fig. 1A discloses a typical prior art automated storage and retrieval system 1 with a frame structure 100 and Figs. 2 and 3A disclose two prior art container handling vehicles 201,301 suitable for operation in such a system 1.

The frame structure 100 comprises vertical members 102, horizontal members 103 and a storage volume comprising storage columns 105 arranged in rows between the vertical members 102 and the horizontal members 103. In these storage columns 105, storage containers 106, also known as “bins”, are stacked on top of each other to form stacks 107. The members 102, 103 may typically be made of metal, for example, extruded aluminum profiles.

The frame structure 100 of the automated storage and retrieval system 1 comprises a rail system 108 disposed across the top of the frame structure 100, upon which rail system 108 a plurality of container handling vehicles 201, 301 are operated to raise the storage containers 106 from, and lower the storage containers 106 to, the storage columns 105, and also to transport the storage containers 106 above the storage columns 105. The rail system 108 comprises a first set of parallel rails 110 arranged to guide movement of the container handling vehicles 201, 301 in a first direction X across the top of the frame structure 100, and a second set of parallel rails 111 arranged perpendicular to the first set of rails 110 to guide movement of the container handling vehicles. 201,301 in a second direction Y which is perpendicular to the first direction X. Container handling vehicles access the containers 106 stored in the columns 105 through access openings/grid openings 112 in the grid cells 122 of the rail system 108. The container handling vehicles 201,301 can travel laterally above the storage columns 105, i.e. in a plane which is parallel to the horizontal plane X-Y.

The vertical members 102 of the frame structure 100 may be used to guide the storage containers during lifting of the containers and lowering of the containers into the columns 105. The stacks 107 of containers 106 are typically self-supporting.

Each container handling vehicle 201,301 of the prior art comprises a vehicle body 201a,301a, and first and second sets of wheels 201b,301b,201c,301c that allow lateral movement of the container handling vehicles 201,301 in the X direction and the Y direction, respectively. Two wheels of each set are fully visible in Figs. 2 and 3A. The first set of wheels 201b,301b is arranged to engage two adjacent rails of the first set of rails 110, and the second set of wheels 201c,301c is arranged to engage two adjacent rails of the second set of rails 111. At least one of the wheel sets 201b, 301b, 201c, 301c can be raised and lowered, so that the first wheel set 201b, 301b and/or the second wheel set 201c, 301c can be engaged with the respective rail set 110, 111 at any time.

Each container handling vehicle 201,301 of the prior art also comprises a lifting device (not shown) for vertically transporting the storage containers 106, e.g., lifting a storage container 106 from, and lowering a storage container 106 to, a storage column 105. The lifting device comprises one or more gripping/engaging devices that are adapted to engage a storage container 106, and which gripping/engaging devices can be lowered from the vehicle 201,301 such that the position of the gripping/engaging devices relative to the vehicle 201,301 can be adjusted in a third direction Z that is orthogonal to the first direction X and the second direction Y. Parts of the gripping device of the container handling vehicle 301 are shown in Fig. 3A and are indicated by reference numeral 304. The gripping device of the container handling device 201 is positioned within the body of the vehicle. 301a in Fig. 2.

Conventionally, and also for the purposes of the present application, Z=1 identifies the topmost layer of storage containers, i.e., the layer immediately below the rail system 108, Z=2 the second layer below the rail system 108, Z=3 the third layer, etc. In the disclosed prior art example of Fig. 1A, Z=8 identifies the lowest bottom layer of storage containers. Likewise, X=1...n and Y=1...n identify the position of each storage column 105 in the horizontal plane. Accordingly, by way of example, and using the Cartesian coordinate system X, Y, Z indicated in Fig. 1A, it can be said that the storage container identified as 106' in Fig. 1A occupies storage position X=10, Y=2, Z=3. It can be said that the container handling vehicles 201,301 move in the Z=0 layer, and each storage column 105 can be identified by its X and Y coordinates.

The storage volume of the frame structure 100 has often been referred to as a grid 104, where the possible storage positions within this grid are referred to as a storage cell. Each storage column may be identified by a position in an X and Y direction, while each storage cell may be identified by a bin number in the X, Y and Z direction.

Each container handling vehicle 201,301 of the prior art comprises a compartment or storage space for receiving and stowing a storage container 106 when the storage container 106 is transported via the rail system 108. The storage space may comprise a cavity centrally arranged within the vehicle body 201a as shown in Fig. 2 and as described in, for example, patent document WO2015/193278A1.

Fig. 3 A shows an alternative configuration of a container handling vehicle 301 with a cantilever construction. Such a vehicle is described in detail in, for example, patent document N0317366 or, for example, patent document WO2019/137870A1.

The central cavity container handling vehicles 201 shown in Fig. 2 may have a footprint covering an area with dimensions in the X and Y directions that is generally equal to the lateral extent of a storage column 105, for example, as described in patent document WO2015/193278A1. The term 'lateral' used herein may mean 'horizontal'.

Alternatively, the central cavity container handling vehicles 101 may have a footprint that is larger than the lateral area defined by a storage column 105, for example, as disclosed in patent document WO2014/090684A1.

The rail system 108 typically comprises rails with grooves into which the vehicle wheels are inserted. Alternatively, the rails may comprise upwardly projecting elements, where the vehicle wheels comprise flanges to prevent derailment. These grooves and upwardly projecting elements are collectively known as tracks. Each rail may comprise one rail, or each rail may comprise two parallel tracks (so-called "double tracks" described in connection with Figs. 1B-1D below).

Patent document WO2018146304 illustrates a typical configuration of the rail system 108 comprising rails and tracks parallel in the X and Y directions.

In the frame structure 100, a majority of the columns 105 are storage columns 105, i.e., columns 105 where the storage containers 106 are stored in stacks 107. However, some columns 105 may have other purposes. In Fig. 1A, columns 119 and 120 are special purpose columns used by container handling vehicles 201, 301 to drop off and/or pick up the storage containers 106 so that they may be transported to an access station (not shown) where the storage containers 106 may be accessed from outside the frame structure 100 or transferred out of or into the frame structure 100. In the art, such a location is typically referred to as a 'port' and the column on which the port is located may be referred to as a 'port column' 119, 120. Transportation to the access station may be in any direction, i.e., horizontal, inclined, and/or vertical. For example, storage containers 106 may be placed in a random or dedicated column 105 within the frame structure 100, then picked up by any container handling vehicle and transported to a port column 119, 120 for further transportation to an access station. Note that the term 'inclined' means transportation of storage containers 106 having a general transportation orientation between horizontal and vertical.

In Fig. 1A, the first port column 119 may be, for example, a dedicated pickup port column where container handling vehicles 201, 301 may drop off storage containers 106 to be transported to an access or transfer station, and the second port column 120 may be a dedicated pickup port column where container handling vehicles 201, 301 may pick up storage containers 106 that have been transported from an access or transfer station.

The access station may typically be a picking or storage station where products are removed from or placed into the storage containers 106. At a picking or storage station, the storage containers 106 are typically not removed from the automated storage and retrieval system 1, but rather are returned back to the frame structure 100 once they have been accessed. A port may also be used to transfer storage containers to another storage facility (e.g., another frame structure or another automated storage and retrieval system), to a transportation vehicle (e.g., a train or a truck), or to a production facility.

To transport the storage containers between the port columns 119,120 and the access station, a transport system comprising conveyors is normally used.

If the port columns 119, 120 and the access station are positioned at different levels, the conveyor system may include a lifting device with a vertical component for transporting the storage containers 106 vertically between the port column 119, 120 and the access station. The conveyor system may be arranged to transfer storage containers 106 between different frame structures, for example, as described in patent document WO2014/075937A1.

When a storage container 106 stored in one of the columns 105 disclosed in Fig. 1A is to be accessed, one of the container handling vehicles 201, 301 is commanded to retrieve the target storage container 106 from its position and transport it to the discharge port column 119. This operation involves moving the container handling vehicle 201, 301 to a location above the storage column 105 in which the storage container 106 is positioned, retrieving the storage container 106 from the storage column 105 using the lifting device of the container handling vehicle 201, 301 (not shown), and transporting the storage container 106 to the discharge port column 119. If the target storage container 106 is positioned at the depth of a stack 107, i.e., with one or more storage containers 106 positioned above the storage container 106 target, the operation also involves temporarily moving the above-placed storage containers before lifting the target storage container 106 from the storage column 105. This step, which is sometimes referred to as “excavation” in the art, may be performed by the same container handling vehicle that is subsequently used to transport the target storage container to the discharge port column 119, or by one or a plurality of other cooperating container handling vehicles. Alternatively, or in addition, the automated storage and retrieval system 1 may have container handling vehicles specifically dedicated to the task of temporarily removing storage containers from a storage column 105. Once the target storage container 106 has been removed from the storage column 105, the temporarily removed storage containers may be returned to the original storage column 105. However, the removed storage containers may alternatively be relocated to other storage columns.

When a storage container 106 is to be stored in one of the columns 105, one of the container handling vehicles 201, 301 is commanded to pick up the storage container 106 from the pickup port column 120 and transport it to a location above the storage column 105 where it is to be stored. Once all of the storage containers placed at or above the target position within the storage column stack 107 have been removed, the container handling vehicle 201, 301 places the storage container 106 in the desired position. The removed storage containers may then be lowered back into the storage column 105, or relocated to other storage columns. One drawback of prior art cantilever type container handling vehicles is that they can only transport one storage container at a time.

An object of the invention is to provide a cantilever type container handling vehicle that can carry more than one storage container at a time.

Summary of the invention

The invention is set forth in the independent claims, while the dependent claims describe alternatives of the invention.

The invention relates to a container handling vehicle for operation on a two-dimensional rail system comprising a first set of parallel rails arranged to guide movement of the container handling vehicles in a first direction X across the top of the frame structure, and a second set of parallel rails arranged perpendicular to the first set of rails to guide movement of the container handling vehicles in a second direction which is perpendicular to the first direction, the first and second sets of parallel rails dividing the rail system into a plurality of grid cells, wherein the container handling vehicle comprises:

- a wheel base unit comprising first and second sets of wheels for guiding the container handling vehicle along the rail system in the first and second directions, respectively, wherein the first and second sets of wheels form outer peripheries of the wheel base unit;

- a body unit comprising:

a lower section provided over the wheel base unit, the lower section having a footprint with a horizontal extent that is equal to or less than the wheel base unit, the lower section having an upper surface, wherein the upper surface provides a first container carrying position for carrying a storage container;

a support section extending vertically from the lower section, the support section having a footprint with a horizontal extent that is smaller than the footprint of the lower section; and a cantilever section extending horizontally from the support section beyond the footprint of the lower section; and

- a lifting device comprising a lifting frame that is suspended from the cantilever section.

In one aspect, when a storage container is positioned on the upper surface, a higher portion of the storage container represents a first height; and the lifting device comprises a lifting frame suspended from the cantilever section, the lifting frame having a lower portion at a second height when the lifting frame is coupled in an upper position adjacent to the cantilever section; wherein the second height, when the lifting frame is coupled in its upper position, is above the first height, such that the lower portion of a coupled lifting frame of a first container handling vehicle is capable of passing over the higher portion of a storage container positioned on the upper surface of a lower section of the body unit of a second container handling vehicle when the first and second container vehicles intersect in adjacent grid cells.

Other robots or human operators can manipulate/pick up items stored in the storage container positioned at the first container transport position. That is, the storage container positioned at the first container transport position could be a useful place to store items that need to be accessed regularly. At the same time, it also provides a useful counterweight for the vehicle when it needs to pick up heavy storage containers.

The first container transport position may be lowered to provide lateral support to a storage container positioned in the first container transport position.

The lifting device may comprise a lifting device motor and at least two lifting shafts, the at least two lifting shafts being arranged in the cantilever section and the lifting device motor being arranged in the lower section, and the lifting device motor and the at least two lifting shafts being connected to one another via a drive coupling. The drive coupling may include all components necessary for transferring rotational motion from the lifting device motor and the lifting shafts.

The lifting device may comprise a lifting device motor and at least two lifting shafts arranged in the cantilever section.

The body unit may comprise an S-shaped housing that connects the lower section, the support section, and the cantilever section together. The S-shape is the shape seen when the housing is viewed from the side.

The first container transport position may comprise a conveyor for transferring a storage container between the first container transport position and an external support. The external support may be an external conveyor. To facilitate transfer of the storage containers, an upper surface of the external support is preferably at the same height as an upper surface of the conveyor in the first container transport position.

A footprint of the lower section of the body unit may be offset relative to the footprint of the wheelbase unit by a width substantially equal to or equal to that of one wheel. In this case, footprint means that the vertical projection of the lower section does not touch an adjacent grid cell when the lower section is arranged directly above a grid cell.

The lifting frame may be suspended on lifting belts, and the lifting frame may extend horizontally and include gripping devices and corner guides, where a lowest point of the corner guides may provide the lowest part of the lifting frame. The lifting belts are preferably electrically and/or signal-conductive, so that the gripping devices of the lifting frame can receive power and instructions.

Further disclosed is an automated storage and retrieval system comprising a two-dimensional rail system comprising a first set of parallel rails arranged to guide movement of container handling vehicles in a first direction X across the top of the frame structure, and a second set of parallel rails arranged perpendicular to the first set of rails to guide movement of the container handling vehicles in a second direction Y that is perpendicular to the first direction, the first and second sets of parallel rails dividing the rail system into a plurality of grid cells, wherein the automated storage and retrieval system comprises a plurality of container handling vehicles as defined above.

The wheelbase unit with the first and second sets of wheels can be equal to one grid cell.

Two container handling vehicles, which have the same orientation, can occupy only three grid cell spaces along a row when they pass each other along that row.

The first set of rails and/or the second set of rails may comprise a single track or a double track comprising two single tracks, and a grid cell may be defined as the horizontal area occupied by a grid opening bounded by the first and second sets of rails, in addition to the area occupied by single tracks in the first and second directions enclosing a single grid opening.

The wheelbase unit may have a footprint equal to a horizontal extent in the first and second directions of a grid cell.

The container handling vehicle may comprise a support surface, wherein the support surface may provide a second container transport position.

The second container transport position can be positioned above the first container transport position. Preferably, the second container transport position has the same vertical projection as the first container transport position. If arranged on a rail system, the size of the support section is preferably equal to or smaller than one grid cell. As an alternative to the second container transport position, two or more storage containers can be stacked on top of each other, with all stacked storage containers supported on the first container transport position.

The second position container transport can move between:

- a retracted position where the second container transport position is beyond a vertical projection of the first container transport position, and

- an extended position where the second container transport position is at or within the vertical projection of the first container transport position.

The second container transport position can be moved between the retracted and extended positions via a pivoting connection. The pivoting connection can be such that:

- in the retracted position, the second surface extends substantially vertically, and.

- in the extended position, the second surface extends horizontally.

Alternatively, the pivot connection may be arranged so that the second surface can be pivoted over the roof of the cantilever section. For example, it could be a hinge connection along the corner edge of the rear portion of the cantilever at the top that connects to that section, the ends of the arms then resting against the vertical surfaces of the support section.

The second container transport position can be moved linearly between the retracted position and the extended position by means of a linear motion arrangement. If a linear motion arrangement is used, the linear motion arrangement can be arranged so that:

- in the retracted position, the second container carrying position moves to a position beyond the first container carrying position and above the cantilever section, and

- In the extended position, the second container transport position is above the first container transport position.

The second container transport position may be provided with a conveyor, i.e., the storage container at the second container transport position may be self-unloaded independently of the storage container at the first container transport position by using the conveyor and some receiving infrastructure that can catch a high-level container exiting the conveyor. If the first container transport position is provided with a conveyor belt, any storage container at the first container transport position may be unloaded without first having to unload the storage container positioned at the second container transport position. If both the first and second container transport positions are provided with conveyor belts, any storage container positioned at the first and/or second container transport positions may be dispatched independently of the other storage container using the conveyor.

Further described is a method of transferring a storage container between a first and a second container handling vehicle as defined above, the first and second container handling vehicles operating in an automated storage and retrieval system comprising a two-dimensional rail system comprising a first set of parallel rails arranged to guide movement of the container handling vehicles in a first X direction across the top of the frame structure, and a second set of parallel rails arranged perpendicular to the first set of rails to guide movement of the container handling vehicles in a second Y direction that is perpendicular to the first direction, the first and second sets of parallel rails dividing the rail system into a plurality of grid cells, wherein the method comprises the steps of:

- using a main control system to command the first and second container handling vehicles to position themselves in neighboring grid cells such that the lifting device of the first container handling vehicle is directly above the upper surface of the lower section of the second container handling vehicle;

- transferring a storage container between the first container transport position of the lower section of the second container handling vehicle and the lifting device of the first container handling vehicle. The transfer of the storage container may be from the first container handling vehicle to the second container handling vehicle, and vice versa.

The step of transferring a storage container between the upper surface of the lower section of the second container handling vehicle and the lifting device of the first container handling vehicle may comprise the steps of:

- configure the container handling vehicle that transports or supports the storage container as the lead vehicle;

- configure the other container handling vehicle as a slave vehicle;

- send a get_bin command to the slave vehicle;

- the slave vehicle executes the get_bin command and updates its internal state when it is confirmed that the storage container is placed on the vehicle;

- the slave vehicle sends a confirmation to the control system when the storage container is in the confirmed position on the vehicle, such that the storage container is sufficiently far from the first container transport position of the master vehicle, preferably with a margin;

- the master vehicle detects that the storage container is gone and will send a bin_update status to the control system;

- The control system updates the logical state to match the physical state of the master vehicle and the slave vehicle.

The get_bin command may include a parameter defining a height of the storage container to be transferred such that the master vehicle's lifting device lowers to a position equal to the highest part of the storage container positioned in the first container transport position. The height of the storage container is the distance between the lifting device in the attached upper position and the top of the storage container. This distance may vary depending on the height of the storage container and whether the storage container is positioned in the first container transport position or in a container transport position at another elevation.

The step of configuring the other container handling vehicle as a slave vehicle may include a step of sending a synchronize_to_master command to the slave vehicle such that the slave vehicle moves with and follows the master vehicle.

After the step of sending a synchronize_to_master command to the slave vehicle, the method may further comprise a step of sending a message from the slave vehicle to the main control system when the slave vehicle moves with and follows the master vehicle.

Further disclosed is a method of transferring a storage container between a container handling vehicle as defined above and an external container transport location, the container handling vehicle operating in an automated storage and retrieval system comprising a two-dimensional rail system comprising a first set of parallel rails arranged to guide movement of the container handling vehicles in a first X direction across a top of a frame structure, and a second set of parallel rails arranged perpendicular to the first set of rails to guide movement of the container handling vehicles in a second Y direction that is perpendicular to the first direction; the first and second sets of parallel rails dividing the rail system into a plurality of grid cells, wherein the method comprises the steps of:

- use a transporter in the first container transport position of the lower section to transfer a storage container between the container handling vehicle and an external position outside the container handling vehicle.

The relative terms "upper", "lower", "below", "above", "higher", etc. shall be understood in their normal sense and as seen in a Cartesian coordinate system.

In the following, numerous specific details are introduced by way of example only to provide a complete understanding of the claimed system and vehicle embodiments. However, one skilled in the art will recognize that these embodiments may be practiced without one or more of the specific details, or with other components, systems, etc. In other instances, well-known structures or operations are not shown, or are not described in detail, to avoid obscuring aspects of the disclosed embodiments. Brief Description of the Drawings

The following drawings are attached to facilitate understanding of the invention.

Fig. 1A is a perspective view of a frame structure of a prior art automated storage and retrieval system;

Fig. 1B-D are top views of a rail system of the container handling vehicle, where Fig. 1B shows a single track rail system, Fig. 1C shows a double track rail system and Fig. 1D shows a double rail system with the width and length of a grid cell of the container handling vehicle indicated;

Fig. 2 is a perspective view of a prior art container handling vehicle having a centrally disposed cavity for transporting storage containers therein; Fig. 3A is a perspective view of a prior art container handling vehicle having an overhang for transporting storage containers therein;

Fig. 3B and 3C show an exemplary wheelbase unit for the container handling vehicle;

Fig. 4A is a simplified side view of a container handling vehicle according to an embodiment of the invention comprising a wheel base unit and a body unit, wherein the body unit comprises a bottom section, a support section and a cantilever section;

Fig. 4B is a perspective view of a container handling vehicle according to an embodiment of the invention where the protective covers have been removed to better illustrate the configuration of components in a bottom section, a support section and a cantilever section of a body unit of the container handling vehicle;

Fig. 4C is a top view of Fig. 4B;

Fig. 4D-4I are exemplary side views of different configurations providing opposite rotation of the lifting shafts;

Fig. 5 is an example of the cantilever section of the body unit, and indicates the parts that may form part of the cantilever section;

Fig. 6 is a simplified side view of a container handling vehicle according to an embodiment of the invention supporting a storage container in a first container transport position and a storage container by means of the lifting device, the container handling vehicle comprising a wheel base unit and a body unit, where the body unit comprises a bottom section, a support section and a cantilever section;

Figs. 7A - 7D show step-by-step an exemplary method of transferring a storage container between a first and a second container handling vehicle operating in an automated storage and retrieval system comprising a two-dimensional rail system; Figs. 8A - 8D show examples of a container handling vehicle according to the invention with a conveyor in the first container transporting position, where Fig. 8A shows a situation when a storage container is not transported in the first container transporting position, Fig. 8B shows a situation with a storage container in the first container transporting position, and Fig. 8C shows a possible transfer of the storage container from the conveyor in the first container transporting position and to an external conveyor, and Fig. 8D shows the conveyor oriented 90 degrees with respect to the conveyor in Fig. 8A;

Fig. 9 shows an example of a container handling vehicle according to the invention comprising an upper surface providing a first container transport position and a support surface providing a second container transport position;

Fig. 10A shows the second container carrier position 426 of Fig. 9 in a retracted position via a pivot connection, such that in the retracted position the second container carrier position is directed upwards;

Fig. 10B shows another example of a possible extended position of the second position of the container carrier;

Fig. 10C shows the example of Fig. 10B where the second container carrier position has been pivoted through 180 degrees and is resting upside down on the cantilever section when in the stowed position; Figs. 11A and 11B show another example of the second container carrier position, where in Fig. 11A the second container carrier position is in the extended position directly above the first container carrying position, and in Fig. 11<b>the second container carrying position is moved to a retracted position by a linear motion arrangement.

In the drawings, similar reference numerals have been used to indicate similar parts, elements or features, unless otherwise explicitly indicated or implied from the context.

Detailed description of the invention

In the following, embodiments of the invention will be discussed in more detail by way of example only and with reference to the accompanying drawings. It should be understood, however, that the drawings are not intended to limit the invention to the subject matter depicted in the drawings.

The frame structure 100 of the automated storage and retrieval system 1 is constructed according to the prior art frame structure 100 described above in connection with Figs. 1A-1D, i.e., a number of vertical members 102 and a number of horizontal members 103, which are supported by the vertical members 102, and further that the frame structure 100 comprises a first upper rail system 108 in the X direction and in the Y direction.

The frame structure 100 further comprises storage compartments in the form of storage columns 105 provided between the members 102, 103, where the storage containers 106 are stackable in stacks 107 within the storage columns 105.

The frame structure 100 may be of any size. In particular, it is understood that the frame structure may be considerably wider and/or longer and/or deeper than that disclosed in Fig. 1A. For example, the frame structure 100 may have a horizontal span of more than 700*700 columns and a storage depth of more than twelve bins.

The rail system 108 may be a single rail system (also referred to as a single track), as shown in Fig. 1B. Alternatively, the rail system 108 may be a double rail system (also referred to as a double track), as shown in Fig. 1C, thereby allowing a container handling vehicle 201 having a footprint generally corresponding to the lateral area defined by an access opening/grid column 112 to travel along a row of grid columns even if another container handling vehicle 201 is positioned above a grid column neighboring that row. Both the single and double track systems, or a combination comprising a single and double track arrangement in a single rail system 108, form a grid pattern in the horizontal plane P comprising a plurality of uniform rectangular grid locations or grid cells 122, where each grid cell 122 comprises a grid opening 115 that is bounded by a pair of tracks 110a, 110b of the first set of rails 110 and a pair of tracks 111a, 111b of the second set of rails 111. In Fig. 1C, the grid cell 122 is indicated by a dashed box. For example, the sections of the rail-based system that are made of aluminum are the rails, and on the upper surface of the rails, there are a pair of tracks on which the wheels of the vehicle run.

However, the sections could be separate rails, each with a track.

Accordingly, tracks 110a and 110b form pairs of rails defining parallel rows of grid cells running in the X direction, and tracks 111a and 111b form pairs of rails defining parallel rows of grid cells running in the Y direction.

As shown in Fig. 1D, each grid cell 122 has a width Wc that is typically within the range of 30 to 150 cm, and a length Lc that is typically within the range of 50 to 200 cm. Each grid opening 115 has a width Wo and a length Lo that is typically 2 to 10 cm less than the width Wc and the length Lc of the grid cell 122.

In the X and Y directions, neighboring grid cells are arranged in contact with each other so that there is no space between them.

Fig. 3A is a perspective view of a prior art container handling vehicle 301 having a cantilever for transporting storage containers underneath.

An exemplary wheel base unit for a container handling vehicle 401 according to the invention is shown in Figs. 3B and 3C. The wheel base unit 2 has a wheel arrangement 32a, 32b having a first set of wheels 32a for movement in a first direction on a rail system 108 and a second set of wheels 32b for movement in a second direction perpendicular to the first direction. Each wheel set comprises two pairs of wheels arranged on opposite sides of the wheel base unit 2. In order to change the direction in which the wheel base unit can travel on the rail system, one of the wheel sets 32b is connected to a wheel travel assembly 7. The wheel travel assembly is capable of raising and lowering the connected wheel set 32b relative to the other wheel set 32a such that only the wheel set traveling in the desired direction is in contact with the rail system. The wheel travel assembly 7 is driven by an electric motor 8. In addition, two electric motors 4,4', powered by a rechargeable battery 6, are connected to the wheel set 32a,32b to move the wheel base unit in the desired direction.

Referring further to Fig. 3B and 3C, the horizontal periphery of the wheel base unit 2 is sized to fit within the horizontal area defined by a grid cell such that two wheel base units 2 can pass past each other in any adjacent grid cell of the rail system 108. In other words, the wheel base unit 2 may have a footprint, i.e., an extent in the X and Y directions, which is generally equal to the horizontal area of a grid cell, i.e., the extent of a grid cell in the X and Y directions, for example, as described in patent document WO2015/193278A1.

Fig. 4A is a simplified side view of a container handling vehicle 401 according to an embodiment of the invention comprising a wheel base unit 2 and a body unit 410, where the body unit 410 comprises a lower section 411, a support section 412 and a cantilever section 413. The lower section 411 has an upper surface, wherein the upper surface 425 provides a first container transport position 425 for transporting a storage container 106.

Referring to Figs. 3B and 4A, the wheel base unit 2 has a top panel/flange 9 (i.e., an upper surface) configured as a connection interface for connecting to a body unit 410 of a container handling vehicle 401. The top panel 9 has a central opening 20 and has multiple through holes 10 (i.e., connection elements) suitable for a bolted connection through corresponding through holes in a lower section 411 of the body unit 401. In other embodiments, the connection elements of the top panel 9 may be, for example, threaded pins for interaction with the through holes of the lower section 411. In yet another embodiment, the container handling vehicle 401 does not have this modular design, but is manufactured in one or more pieces. The presence of a central opening 20 is advantageous, as it provides access to the internal components of the wheel base unit 2, such as the rechargeable battery 6 and an electronic control system 21.

Referring further to Fig. 4A, it is disclosed that the body unit 410 comprises an S-shaped housing that joins the lower section 411, the support section 412 and the cantilever section 413 together. The container handling vehicle 401 of Fig. 4A is operable on a rail system 108 as described in connection with Figs. 1A-1D, and comprises a wheel base unit 2 and a body unit 410. The wheel base unit 2 comprises wheelsets 32a, 32b for guiding the container handling vehicle 401 along the rail system 108 in the first and second directions X, Y. The body unit 410 comprises a bottom section 411, a support section 412, and a cantilever section 413. The bottom section 411 is mounted to an upper surface of the wheel base unit 2. The bottom section 411 may have a footprint with a horizontal extent equal to or less than the horizontal extent of one of the grid cells 122. The top of the storage container 106 is at a first height h1. That is, the first height h1 is the distance from the top of the rail system 108 to the top of the storage container 106 positioned in the first container transport position on the upper surface of the lower section 411 when the lower section 411 is mounted on the wheel base unit 2. The support section 412 extends vertically from the lower section 411 and has a footprint with a horizontal extent that is smaller than the footprint of the lower section 411. The width of the support section 412 (i.e., the extent in the X direction) may be equal to the width of the lower section 411 (in the X direction). The extent of the support section 412 in the Y direction is smaller than the extent of the lower section 411 in the Y direction.

Furthermore, referring to Fig. 4C, when viewed in a top plan view, the footprint of the support section 412 falls within the footprint of the lower section 411. In other words, as disclosed in Figs. 4A-4C, the support section 412 does not extend beyond the lower section 411. The cantilever section 413 extends horizontally from the support section 412 beyond the footprint of the lower section 411 and comprises a lifting device 414 suspended from the cantilever section 413.

The lifting device 414 comprises a lifting frame 415 having a lower portion at a second height h2 when the lifting frame 415 is coupled in an upper position adjacent to the cantilever section 413 (Figs. 4A and 4B show the coupled position of the lifting frame 415). That is, the second height h2 is the distance from the top of the rail system 108 to the lowest part of the lifting frame 415. The lifting frame 415 is suspended from the cantilever section 413 by lifting straps 419. The lifting frame 415 may comprise gripping devices 420 extending from a bottom surface thereof for connecting the lifting frame to complementary lifting holes of the storage containers 106, thereby making lifting and lowering of the storage containers 106 possible. In addition, the lifting frame 415 may comprise guides 421 arranged at the corners of the bottom surface of the lifting frame 415 for aligning the gripping devices 420 of the lifting frame 415 with respect to the complementary lifting holes of the storage containers 106. In many situations, the guides 421 or the gripping devices 420 may constitute the lowest part of the lifting frame. lifting frame 415, such that the second height h2 is the lowest part of any of these components. However, according to one embodiment of the invention, the second height h2 of the lowest part of the lifting frame 415, when the lifting frame 415 is coupled in its upper position, is always above the first height h1 of the storage container 106 positioned in the first container transport position.

By ensuring that the lowest part of a coupled lifting frame 415 of a first container handling vehicle 401 can pass over a storage container 106 supported in the first container transport position of a second container handling vehicle 401 when the first and second container vehicles 401 pass each other in adjacent grid cells 122, the first and second container handling vehicles 401 can pass each other while collectively occupying fewer grid cells than required in prior art solutions.

Fig. 4B is a perspective view of a container handling vehicle 401 according to the embodiment of the invention where the protective covers have been removed to better illustrate the configuration of the components in the lower section 411, the support section 412 and the cantilever section 413 that constitute the body unit 410 of the container handling vehicle 401. In the embodiment of Fig. 4B, it is disclosed that the lifting device 414 comprises a lifting device motor 416' and at least two lifting shafts 417', 417''. The two lifting shafts 417',417'' are arranged in parallel on the cantilever section 413. Lifting straps 419 connected to the lifting frame 415 are wound and unwound on the lifting shafts 417',417'', thereby moving the lifting frame 416 and any storage containers 106 carried by the lifting frame 415 up and down. Lifting shaft wheels 423',423'' are disposed at each end of the lifting shafts 417 and operate in conjunction with the lifting shafts 417, respectively. As shown in Fig. 4B , the lifting device motor 416' is arranged in the lower section 411. The lifting device motor 416' and the two lifting shafts 417 are connected to each other via lifting shaft wheels 423', 423'' and an endless flexible force transfer element 418, such as, for example, a belt, which runs through pulleys 422 to ensure that the first and second lifting shafts 417 rotate simultaneously in the same direction. Any necessary power source (not shown) for supplying power to the lifting device motor 416' may be arranged in the lower section 413 in order to obtain a favorable center of gravity with a reduced risk of tilting of the container handling vehicle in case of lifting a heavy storage container 106 and/or as a result of too high acceleration/deceleration of the container handling vehicle 401.

The lifting frame 415 is shown with guides 421 arranged at the corners of the lower surface of the lifting frame 415 to align the gripping devices 420 of the lifting frame 41 with respect to the complementary lifting holes of the storage containers 106.

Any necessary power source (not shown) for supplying power to the motor of the lifting device 416'' may be arranged in the lower section 413 in order to obtain a favorable center of gravity with reduced risk of tilting of the container handling vehicle in case of lifting of a heavy storage container 106 and/or as a result of too high acceleration/deceleration of the container handling vehicle 401.

Fig. 4C is a top view of Fig. 4B, showing the bottom section 411, the support section 412, and the cantilever section 413.

Fig. 4D-4I are examples of different configurations providing opposite rotation of the lifting shafts 417', 417''. As disclosed in all examples of Fig. 4D-4I, common to all force transfer configurations is the presence of a rotating lifting device motor 416', a first and second lifting shaft wheel 423', 423'' each of which is connected for rotation with the respective lifting shafts 417', 417'', at least one pulley 422', 422'', a force transfer element 418 in the form of an endless belt forming a closed loop and where at least one of the pulleys 422', 422'' is arranged within the closed loop. Furthermore, the first or second lifting shaft wheel 423',423'' is in contact with an inner surface of the endless belt 418 and the other of the first or second lifting shaft wheel 423',423'' is in contact with the outer surface of the endless belt 418. This is achieved by arranging one of the first or second lifting shaft wheels 423',423'' within the closed loop formed by the force transfer element 418 and the other of the first or second lifting shaft wheel 423',423'' outside the closed loop formed by the force transfer element 418. The mutual configuration of the first and second lifting shaft wheels 423',423'' (e.g., acting on opposite sides of the endless belt), the guide pulleys 422',422'' and the force transfer element 418, is such that the first and second lifting shafts 417', 417'' (via the first and second lifting axle wheels 423', 423'', respectively) rotate in opposite directions (counter-rotation). The first and second lifting axle wheels 423', 423'' are preferably arranged in the same horizontal plane to ensure horizontal stability during lifting. The pulley(s) 422',422'' are arranged along the stroke of the force transfer element 418 in fixed positions so as to allow a "change" in the stroke direction of the force transfer element 418. Each of the pulleys 422',422'' are arranged to correctly drive the force transfer element 418 over the first and second lift shaft wheels 423',423'' thereby allowing the first and second lift shaft wheels 423',423'' (and therefore the lift shafts 417',417'') to rotate in opposite directions.

In the example in Fig. 4D, a 422' pulley is shown.

In the examples of Fig. 4E-4I, various examples of force transfer configurations comprising two pulleys 422', 422'' are shown. The pulleys 422', 422'' are alternately arranged along the path of the force transfer element 418 such that the first wheel of the lifting shaft 423' is followed by a pulley 422', 422'' and the second wheel of the lifting shaft 423'' is followed by a pulley 422', 422'' in both directions of travel of the force transfer element 418.

In the examples of Fig. 4G, 4H, 4I, examples are disclosed comprising a tensioning wheel 424 for tensioning the force transfer element 418. The tensioning wheel 424 may be, for example, an eccentric tensioning mechanism comprising a rotatable pulley with an axis that can be fitted within an opening in a fixed support. The location of the tensioning wheel 424 along the path of the force transfer element 418 is preferably at a location where the length of the path of the force transfer element 418 can be affected (i.e., the path of the force transfer element can be shortened or lengthened in order to further tension or reduce the tension in the force transfer element). The tensioning wheel 424 may be arranged inside (Fig. 4G and 4I) or outside (Fig. 4H) of the closed loop formed by the force transfer element 418.

In the examples of Fig. 4D-4F, a dedicated tensioning mechanism such as an idler wheel is not shown; however, if a tensioning mechanism is required, one of the pulleys 422' or 422'' may be a tensioning mechanism and may be replaced by an idler wheel 424.

Fig. 5 is an example of another configuration of the lifting device 414, where, in addition to the lifting shafts 417 and the lifting straps that can be wound on and off the lifting shafts 417', 417'', also the lifting device motor 416'' is arranged on the cantilever section 413 of the body unit 410. The lifting device motor(s) 416'' in Fig. 5 is a brushless DC motor that surrounds one of the lifting shafts 417', 417''. Synchronous operation of the lifting shafts 417', 417'' can be achieved by a synchronizing element such as a force transfer element as disclosed in Figs. 5A-5E and 6A-6H in patent document WO 2019/137870 A1 (applicant: Autostore Technology AS).

Fig. 6 is a simplified side view of a container handling vehicle 401 according to an embodiment of the invention supporting a storage container 106 in a first container transport position 425 and a storage container 106 by means of the lifting device 415, the container handling vehicle 401 comprising a wheel base unit 2 and a body unit, where the body unit comprises a bottom section 411, a support section 412 and a cantilever section 413. The components of the container handling vehicle of Fig. 6 are similar to those of the container handling vehicle of Fig. 4A. The first container transport position 425 is preferably recessed to provide lateral support to a storage container 425 positioned in the first container transport position 425.

Figs. 7A - 7D show step by step an exemplary method of transferring a storage container 106 between a first and a second container handling vehicle 401 operating in an automated storage and retrieval system 1 comprising a two-dimensional rail system 108. Referring to Fig. 7A, a first container handling vehicle 401 (i.e., the right-hand vehicle in the figure not carrying a storage container 106) is positioned at a distance from the second container handling vehicle 401 (i.e., the left-hand vehicle in the figure carrying a storage container 106 on the lifting device and carrying a storage container 106 at the first container transporting position 425). The first container handling vehicle 401 and the second container handling vehicle 401 operate in neighboring rows on the rail system 108.

In Fig. 7B, the first and second container handling vehicles 401 have moved closer to each other compared with the situation in Fig. 7A, and the lifting device 414 of the first container handling vehicle 401 is almost above the upper surface/first container carrying position 425 of the lower section 411 of the second container handling vehicle 401.

In Fig. 7C, the first and second container handling vehicles 401 have been positioned in neighboring grid cells 122 such that the lifting device 414 of the first container handling vehicle 401 is directly above the upper surface/first container transport position 425 of the lower section 411 of the second container handling vehicle 401.

In Fig. 7D, the lifting device 414 of the first container handling vehicle 401 has been lowered to lift the storage container 106 positioned at the first container transport position 425 from the second container handling vehicle 401 and has lifted the storage container 106 from the first container transport position 425. The transfer of the storage container 106 is now complete.

Referring to Fig. 7A - 7D, the storage container transfer method may comprise the steps of:

- using a main control system to command the first and second container handling vehicles 401 to position themselves in neighboring grid cells 122 such that the lifting device 414 of the first container handling vehicle 401 is directly above the upper surface of the lower section 411 of the second container handling vehicle 401;

- transferring a storage container 106 between the first container transport position 425 of the lower section 411 of the second container handling vehicle 401 and the lifting device 414 of the first container handling vehicle 401. The step of transferring a storage container 106 between the upper surface of the lower section 411 of the second container handling vehicle 401 and the lifting device 414 of the first container handling vehicle 401 may comprise the steps of:

- configure the container handling vehicle 401 that transports or supports the storage container 106 as the main vehicle;

- configure the other container handling vehicle 401 as a slave vehicle;

- send a get_bin command to the slave vehicle;

- the slave vehicle executes the get_bin command and updates its internal state when it is confirmed that the storage container 106 is placed on the vehicle 401;

- the slave vehicle sends a confirmation to the control system when the storage container is in the confirmed position on the vehicle such that the storage container 106 is sufficiently far from the first container transport position 425 of the master vehicle;

- the master vehicle detects that the storage container 106 is gone and will send a bin_update status to the control system 500;

- The control system 500 updates the logical state to match the physical state of the master vehicle and the slave vehicle.

The get_bin command may include a parameter defining a height of the storage container 106 to be transferred such that the lifting device 414 of the master vehicle descends to a position equal to a highest part of the storage container placed in the first container transport position.

The step of configuring the other container handling vehicle 401 as a slave vehicle may comprise the step of sending a synchronize_to_master command to the slave vehicle, such that the slave vehicle moves with and follows the master vehicle. This allows the storage container 106 to be transferred between the upper surface of the lower section 411 of the second container handling vehicle 401 and the lifting device 414 of the moving first container handling vehicle 401. The slave vehicle may optionally send a message to the main control system when synchronization has been obtained. Alternatively, the main control system may determine that synchronization has been obtained based on positional information of the slave vehicle and the master vehicle. Synchronization has been obtained when the slave vehicle moves with and follows the master vehicle.

The master vehicle may send motion data, such as velocity, acceleration, and position, to the slave vehicle. The slave vehicle may use the motion data to synchronize its own movements with the received motion data. The master vehicle may send the motion data through the main control system. The master vehicle may, alternatively or additionally, send the motion data directly to the slave vehicle using local communication between the master vehicle and the slave vehicle. The local communication may be any suitable means of local wireless communication, such as near field communication (NFC) or infrared (IR).

The synchronized movement of the slave vehicle and the master vehicle may include train-type synchronization in which the slave vehicle follows the master vehicle, or the synchronized movement may include parallel synchronization in which the slave vehicle moves with the master vehicle side by side.

The automated storage and retrieval system may include a positioning system that uses multilateration techniques, such as a time-of-flight (TOF) measurement system, to determine the position of both the master vehicle and the slave vehicle. The main control system continuously receives position data from the positioning system of a position of the first container handling vehicle and position data of a position of the second container handling vehicle. The main control system may use the position data to command the slave vehicle to move with and follow the master vehicle within a predetermined separation from the master vehicle. The movement of the master vehicle and the slave vehicle is synchronized such that the step of transferring the storage container 106 between the upper surface of the lower section 411 of the second container handling vehicle 401 and the lifting device 414 of the first container handling vehicle 401 may be performed in motion.

The container handling vehicles may be equipped with sensors that can detect the position of the container handling vehicles on the rail system, and/or proximity sensors that detect the distance to nearby container handling vehicles. The main control system may command the slave vehicle to move with the master vehicle and follow it within a predetermined separation from the master vehicle based on distance data received from the proximity sensor of the slave vehicle. The movement of the master vehicle and the slave vehicle is synchronized such that the step of transferring the storage container 106 between the upper surface of the lower section 411 of the second container handling vehicle 401 and the lifting device 414 of the first container handling vehicle 401 can be performed in motion.

The container handling vehicles may be adapted to move together in physical contact with each other. The main control system may command the slave vehicle to move with and follow the master vehicle by first moving in physical contact with the master vehicle, and after contact continuing to apply a pushing force on the master vehicle to maintain physical contact. The movement of the master vehicle and the slave vehicle is synchronized such that the step of transferring the storage container 106 between the upper surface of the lower section 411 of the second container handling vehicle 401 and the lifting device 414 of the first container handling vehicle 401 can be performed in motion.

Figs. 8A - 8D show examples of a container handling vehicle 401 according to an embodiment of the invention with a conveyor 427 in the first container transport position 425 adapted to transfer the storage container 106 rearwardly to another container handling vehicle or to an external conveyor via either of the short sides of the container handling vehicle 401. The conveyor 427 could also have been oriented 90 degrees relative to the embodiment of Fig. 8A such that the storage containers 106 could be transferred directly rearwardly to another container handling vehicle or to an external conveyor (see Fig. 8D). Fig. 8A shows a situation in which no storage container is carried in the first container transport position 425, while Fig. 8B shows a situation with a storage container 106 in the first container transport position 425, and Fig. 8C shows a possible transfer of the storage container 106 from the conveyor 427 in the first container transport position 425 and to an external conveyor 428. An upper surface of the external conveyor 428 is preferably arranged at a height substantially equal to that of an upper surface of the conveyor 427 in the first container carrier position 425.

Referring to Figs. 7A, 7B and 8A, the lower section 411 has an upper surface 425 that is recessed relative to a pair of support bands 429, wherein the upper surface 425 provides the first container transport position 425 for transporting a storage container 106. The support section 412 extends vertically from the pair of support bands 429 of the lower section 411, the support section 412 having a footprint with a horizontal extension that is less than the footprint of the lower section 411.

Fig. 9 shows an example of a container handling vehicle 401 according to an embodiment of the invention comprising an upper surface 425 providing a first container transport position 425 and a support surface 426 providing a second container transport position 426. The container handling vehicle 401 of Fig. 9 comprises components similar to those of the container handling vehicle of Figs. 4A and 6 , which will not be repeated herein. However, the container handling vehicle 401 of Fig. 9 additionally comprises the second container transport position 426. The second container transport position 426 is disclosed as being disposed above the first container transport position 425. Preferably, the first and second container transport positions 425, 426 form the same vertical projection onto the underlying rail system 108.

Fig. 10A shows the second container transport position of Fig. 9 in a retracted position via a pivot connection 430 such that in the retracted position the second container carrier position 426 is directed upwards. Arrow A shows the direction of movement from an extended horizontal position (in Fig. 9) and a vertical retracted position in Fig. 10A. The pivot connection 430 shows the axis of rotation of the second container carrier 426.

Fig. 10B shows another example of a possible extended position of the second container carrier position 426. In Fig. 10B, the second container carrier position 426 is in the extended horizontal position in which it can receive a storage container (not shown).

Fig. 10C shows the example of Fig. 10B where the second container carrier position 426 has been pivoted 180 degrees and rests upside down on the cantilever section 413 of the container handling vehicle 401 when in the retracted position. The second container transport position 426 has been pivoted from the retracted position to the extended position about the pivoting connection arrangement 430 as shown by arrow A.

Fig. 11A and 11B show another example of the second container carrier position 426, where, in Fig. 11A, the second container carrier position 426 is in the extended position directly above the first container transport position 425, and in Fig. 11B, the second container transport position is moved linearly (as indicated by arrow A) to a retracted position by means of a linear motion arrangement (not shown).

Therefore, referring to Fig. 10A, 10B, 10C and 11A and 11B, to access a storage container 106 positioned in the first container transport position 425, the second container transport position 426 is preferably movable between:

- a retracted position where the second container transport position 426 is beyond a vertical projection of the first container transport position 425, providing access to the upper surface of the first container transport position 425 and/or to the storage container 106 positioned in the first container transport position 425, and

- an extended position where the second container carrying position 426 is at or within the vertical projection of the first container carrying position 425. The second container carrying position 426 may be movable between the retracted position and the extended position via a pivoting connection arrangement 430 (Fig. 10A-10C)) or a linear motion arrangement (Fig. 11A and 11B) where it is linearly movable between the retracted position and the extended position via a linear motion arrangement.

If a pivot connection is used (see Fig. 10A-10C), the pivot connection 430 may be arranged so that:

- in the retracted position, the second container carrying position 426 is substantially vertical, and - in the extended position, the second container carrier position 426 extends substantially horizontally.

If a linear motion arrangement is used (see Fig. 11A and 11B), the linear motion arrangement may be arranged so that:

- in the retracted position, the second container transport position 426 is moved to a position beyond the first container transport position 425 and above the cantilever section 413, and - in the extended position, the second container transport position 426 is above the first container transport position 425.

In the preceding description, various aspects of an automated storage and retrieval system according to the invention have been described with reference to the illustrative embodiment. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the system, which are apparent to those skilled in the art, are considered to be within the scope of the present invention, as defined by the following claims. List of reference numerals

h2__________ | Second height

Claims (15)

1. A container handling vehicle (401) for operation on a two-dimensional rail system (108) comprising a first set of parallel rails (110) arranged to guide movement of container handling vehicles (401) in a first direction (X) across the top of a frame structure (100), and a second set of parallel rails (111) arranged perpendicular to the first set of rails (110) to guide movement of the container handling vehicles (401) in a second direction (Y) that is perpendicular to the first direction, the first and second sets of parallel rails (110, 111) dividing the rail system (108) into a plurality of grid cells (122), wherein the container handling vehicle (401) comprises: - a wheel base unit (2) comprising first and second sets of wheels (32a, 32b) for guiding the container handling vehicle (401) along the rail system (108) in the first and second directions (X, Y) respectively, wherein the first and second sets of wheels (32a, 32b) form outer peripheries of the wheel base unit (2); - a body unit (410) comprising: a lower section (411) provided on the wheel base unit (2), the lower section (411) having a footprint with a horizontal extension that is equal to or less than the wheel base unit (2), the lower section (411) having an upper surface, the upper surface (425) providing a first container transport position (425) for transporting a storage container (106); a support section (412) extending vertically from the lower section (411), the support section (412) having a footprint with a horizontal extension that is smaller than the footprint of the lower section (411); and a cantilever section (413) extending horizontally from the support section (412) beyond the footprint of the lower section (411); and - a lifting device (414) comprising a lifting frame (415) that is suspended from the cantilever section (413). 2. The container handling vehicle (401) according to claim 1, wherein, when a storage container (106) is placed on the upper surface, a higher part of the storage container (106) represents a first height (h1); and the lifting device (414) comprises a lifting frame (415) which is suspended from the cantilever section (413), the lifting frame (415) having a lower part at a second height (h2) when the lifting frame (415) is coupled in an upper position adjacent to the cantilever section (413); wherein the second height (h2), when the lifting frame (415) is coupled in its upper position, is greater than the first height (h1), such that the lowest part of a coupled lifting frame (415) of a first container handling vehicle (401) can pass over the highest part of a storage container (106) positioned on the upper surface of a lower section (411) of the body unit (410) of a second container handling vehicle (401) when the first and second container handling vehicles (401) pass past each other in adjacent grid cells (122). 3. The container handling vehicle (401) according to any of the preceding claims, wherein the first container transport position (425) is lowered to provide lateral support to a storage container (106) positioned in the first container transport position (425). 4. The container handling vehicle (401) according to any one of the preceding claims, wherein the lifting device (414) comprises a lifting device motor (416') and at least two lifting shafts (417), and wherein the at least two lifting shafts (417) are arranged in the cantilever section (413) and the lifting device motor (416') is arranged in the lower section (411), and wherein the lifting device motor (416') and the at least two lifting shafts (417) are connected to each other through a drive coupling (418). 5. The container handling vehicle (401) according to any of the preceding claims, wherein the lifting device (414) comprises a lifting device motor (416'') and at least two lifting axles (417) arranged in the cantilever section (413). 6. The container handling vehicle (401) according to any of the preceding claims, wherein the body unit (410) comprises an S-shaped shell joining the lower section (411), the support section (412) and the cantilever section (413) together. 7. The container handling vehicle (401) according to any of the preceding claims, wherein the first container transport position (425) comprises a conveyor (427) for transferring a storage container (106) between the first container transport position (425) and an external support. 8. The container handling vehicle (401) according to any of the preceding claims, wherein a footprint of the lower section (413) of the body unit (410) is offset relative to the footprint of the wheel base unit (2) by a width substantial or equal to that of a wheel (32a, 32b). 9. The container handling vehicle (401) according to any of the preceding claims, wherein the lifting frame (415) is suspended on lifting belts (419), and wherein the lifting frame (415) extends horizontally and comprises gripping devices (420) and corner guides (420), wherein a lowest point of the corner guides (420) provides the lowest part of the lifting frame (415). 10. The container handling vehicle (401) according to any of the preceding claims, wherein the container handling vehicle (401) comprises a support surface (426), wherein the support surface (426) provides a second container transport position (426). 11. The container handling vehicle (401) according to claim 10, wherein the second container transport position (426) is arranged above the first container transport position (425). 12. An automated storage and retrieval system (1) comprising a two-dimensional rail system (108) comprising a first set of parallel rails (110) arranged to guide movement of container handling vehicles (401) in a first direction (X) across the top of the frame structure (100), and a second set of parallel rails (111) arranged perpendicular to the first set of rails (110) to guide movement of the container handling vehicles (401) in a second direction (Y) that is perpendicular to the first direction, the first and second sets of parallel rails (110,111) dividing the rail system (108) into a plurality of grid cells (122), wherein the automated storage and retrieval system comprises a plurality of container handling vehicles (401) according to any one of the preceding claims. 13. A method of transferring a storage container (106) between a first and a second container handling vehicle (401) according to any one of claims 1-11 operating in an automated storage and retrieval system comprising a two-dimensional rail system (108) comprising a first set of parallel rails (110) arranged to guide movement of container handling vehicles (401) in a first direction (X) across the top of the frame structure (100), and a second set of parallel rails (111) arranged perpendicular to the first set of rails (110) to guide movement of the container handling vehicles (401) in a second direction (Y) that is perpendicular to the first direction, the first and second sets of parallel rails (110,111) dividing the rail system (108) into a plurality of grid cells (122), wherein the method comprises the steps of: - using a main control system to command the first and second container handling vehicles (401) to position themselves in neighboring grid cells (122) such that the lifting device (414) of the first container handling vehicle (401) is directly above the upper surface of the lower section (411) of the second container handling vehicle (401); - transferring a storage container (106) between the first container transport position of the lower section (411) of the second container handling vehicle (401) and the lifting device (414) of the first container handling vehicle (401). 14. Method according to claim 13, wherein the step of transferring a storage container (106) between the upper surface of the lower section (411) of the second container handling vehicle (401) and the lifting device (414) of the first container handling vehicle (401) comprises the steps of: - configure the container handling vehicle (401) that transports or supports the storage container (106) as a master vehicle; - configure the other container handling vehicle as a slave vehicle; - send a get_bin command to the slave vehicle; - the slave vehicle executes the get_bin command and updates its internal state when it is confirmed that the storage container is placed on the vehicle; - the slave vehicle sends a confirmation to the control system when the storage container is in the confirmed position on the vehicle, such that the storage container is sufficiently far from the first container transport position of the master vehicle; - the master vehicle detects that the storage container is gone and will send a bin_update status to the control system; - The control system updates the logical state to match the physical state of the master vehicle and the slave vehicle. 15. Method of transferring a storage container between a container handling vehicle (401) according to any of the preceding claims 1-11 and an external container transport position, the container handling vehicle operating in an automated storage and retrieval system comprising a two-dimensional rail system (108) comprising a first set of parallel rails (110) arranged to guide movement of the container handling vehicles (401) in a first direction (X) across the top of the frame structure (100), and a second set of parallel rails (111) arranged perpendicular to the first set of rails (110) to guide movement of the container handling vehicles (401) in a second direction (Y) that is perpendicular to the first direction, the first and second set of parallel rails (110,111) dividing the rail system (108) into a plurality of grid cells (122), wherein the first and second set of parallel rails (110,111) are arranged perpendicular to the first set of rails (110) to guide movement of the container handling vehicles (401) in a second direction (Y) that is perpendicular to the first direction. method comprises the stages of: - using a conveyor in the first container transport position of the lower section (411) to transfer a storage container (106) between the container handling vehicle (401) and an external position outside the container handling vehicle (401).